In the past, angle of arrival meters have not had the capability of eliminating retro reflection which would enable one at the source to be able to determine that his signal was being looked at. Therefore, this invention is provided for the purpose of detecting the relative angular location of a radiation source within the field of view of the device without retro reflection of received radiation. The present invention eliminates a sometimes-objectable characteristic of the earlier invention, that of retro reflection. In certain applications such as military applications, it is not permissible to present such a retro reflection.
An important characteristic of this invention is that it does not focus, or gather and concentrate incident radiation. For this reason, this invention is useful mainly for strong sources of direct radiation, and will not have sufficient sensitivity to detect very weak sources, such as from diffuse reflectors, scatterers, etc. At the same time, this can be an advantage when the source radiation can be very strong, as from the sun, such that a focusing system's detectors would be damaged. The dynamic range of this invention is the same as for focused systems, but is much lower on an absolute scale. The present invention is such that the essential elements of the reflection mirrors can be presented in several varied configurations so that each will eliminate retro reflection as desired.